The present inventions are related to systems and methods for utilizing multi-bit memory cells, and more particularly to systems and methods for variable life usage of multi-bit memory cells.
Flash memories have been used in a variety of devices where information stored by the device must be maintained even when power is lost to the device. A typical flash memory exhibits a number of cells that can be charged to one of 2N distinct voltage levels representing ‘N’ bits per cell. For example, a two bit cell may be charged to one of four distinct voltage levels each representing a corresponding two bit pattern (i.e., 00, 01, 10, 11). By allowing each cell to represent more than a single bit, the memory density of a given flash device can be increased dramatically for the cost of a few additional comparators and a reasonable increase in write logic. Currently, there is a trend toward further increasing the number of bits that may be stored in any given cell by increasing the number of distinct voltage levels that may be programmed to the cell. For example, there is a trend toward increasing the number of distinct voltage levels to eight so that each cell can hold three data bits. While the process of increasing the number of bits stored to any given flash memory cell allows for increasing bit densities, it can result in a marked decline in the lifecycle of the flash memory. In some cases, this decline in lifecycle of a memory device is unacceptable.
Hence, for at least the aforementioned reason, there exists a need in the art for advanced systems and methods for implementing memories.